Propeller pitch change motor



J. EJAN'DERLSCN -ETAL 2,573,783

PROPELLER, PITCH CHANGE MOTOR Nov. 6,' 1951 6 Sheets-Sheet 1 Original File'd Feb. 4, 1943 ATTORNEY Nov. 6, 1951 J. E. ANDERSON ETAL 3,

PROPELLER PITCH CHANGE MOTOR Original Filed Feb. 4, 1943 6 Sheets-Sheet 2 ATTORNEY J. E. ANDERSON ETAL 2,573,783

Nov. 6, 1951;

PROPELLER PITCH CHANGE MOTOR 6 Sheets-Sheet 3 Original Filed Feb. 4, 1943 ATTORNEY Nov. 6,1951 J. E. ANDERSON El'AL 2,573,783

- PROPELLER PITCH CHANGE MOTOR Original Filed Feb. 4, 1943 6 Sheets-Sheet 4 ATTORNEY Nov. 6, 1951 J. E. ANDERSON ET AL 2,573,783

I PROPELLER PITCH CHANGE MOTOR Original Filed Feb. 4, 194:5 e Sheet-Sheet 5 INVENTORS ATTORNEY Nov. 6, 1951 J. E. ANDERSON I ET AL 2,573,783

PROPELLER PITCH CHANGE MOTOR Original Filed Feb. 4, 1943 6 Sheets-Sheet 6 INVENTQRS TORNEY Patented Nov. 6, 1951 UNITED STATES PATENT OFFICE PROPELLER- PITCH CHANGE MOTOR John E. Anderson, Portland, and Arthur N. Allen, Jr., East Windsor Hill, Conn., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware This application is a division of United States application Serial No. 474,638, filed February 4, 1943, by John E. Anderson and Arthur N. Allen, Jr., for Propellers, now Patent No. 2,533,415, issued December 12, 1950.

This invention relates to improvements in hydro-controllable aeronautical propellers and has particular reference to an improved hydraulic motor for changing the propeller pitch.

An object of the invention resides in the provision of a motor so small in size that one may be placed in the base end of each blade, the motor being capable of utilizing hydraulic fluid at extremely high pressures.

A further object resides in the provision of improved fiuidtight seals within the motor for preventing leakage of the extremely high pressure fluid, and capable of withstanding the severe service to which they are subjected.

A still further object resides in the provision of motors of the character indicated which can be completely assembled and tested outside of the propeller and subsequently incorporated as units in the propeller combination.

Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawings, in which like reference numerals are utilized to designate similar parts throughout, there is illustrated a suitable mechanical embodiment for the purpose of disclosing the invention.

Fig. 1 is a sectional view through a propeller hub, showing a pitch changing motor constructed according to the invention, and diagrammatically illustrating a hydraulic system for operating the motors.

Fig. 2 is a transverse sectional view on the line 22 of Fig. 1.

Fig. 3 is a sectional view of a fragmentary portion of the propeller taken on the line 3-3 of Fig. 2 and showing in detail the wedge construction for preloading the blade retaining bearings.

Fig. 4 is a transverse sectional view on the line 44 of Fig. 1 particularly illustrating some of the connections between the fluid motors and the hub-included portion of the hydraulic system.

Fig. 5 is a transverse sectional view on the line 5-5 of Fig. 1 showing details of one of the hydraulic motors.

Fig. 6 is a bottom view of a propeller blade with a hydraulic motor constructed according to the invention assembled therein.

9 Claims. (Cl. 170-46033) Fig. 7 is a front elevational view, similar to Fig. 2, of the center portion of a propeller constructed according to the invention, a portion being broken away and shown in section, to illustrate a somewhat modified form of motor and blade retention means.

The propeller has a hub 10 mounted on shaft l2 of the engine [4. The hub is splined to shaft l2 as indicated at 16, and is held in operative position on the shaft by cones I8 and 20, and nut 22 threaded onto shaft 12. The hub has blade-retaining sockets 24, 26 and 28 (Fig. 2) which receive blades 30, 32 and 34. The blades are retained in the sockets by stacked thrust ball bearings, as indicated at 36, 38, 49 and 42, in circumferential seats in the interior of each blade socket and on the exterior of each blade shank. It will be noted from Figs. 1 and 2 that the grooves in the blades are somewhat elongated in cross-section, the arrangement being such that if the blades are moved radially inwardly from their operative positions the bearing balls may be inserted through holes 44, 46 and 48 into the grooves and thereafter the blades may be restored to their operative positions as in Fig. 1. After the balls have been inserted the holes are closed by screw plugs 50 to prevent entry of dirt and. to retain lubricant. No holes have been provided for the bottom row of balls 42 since the balls of this row may be inserted from the inside of the hub. The movement or the blades from the inward position in which the balls are inserted to the outward position in which they are retained in operative position is controlled by a wedge arrangement indicated at 52 in Fig, 1 and particularly illustrated in Fig. 3, the detailed construction and operation of which will later appear.

Each servo-motor comprises an outer rotatable sleeve-like member 54 (Fig. 5) and an inner member 65, the outer member 54 having two diametrically opposed inwardly projecting vanes 56 and 58 and the inner member 65 having two diametrically opposed outwardly projecting abutments 62 and 64 of the same length as 56 and 58, the difference between the external diameter of the inner member and the inner diameter of the outward member being the depth of the vanes and abutments. The outer rotatable sleeve-like member 54 is provided with means such as splines 84 to prevent motion relative to the blade 30, and the inner member 65 has similar means 66 (Fig. 1) for preventing motion relative to stationary member 60.

Stationary member is provided with an outwardly extended radial flange 6| (Fig. 1). The outer member 54 has a shoulder 63 forming a recess extending somewhat beyond the depth of vanes 56.and.-58-and in line with the ends of the vanes whicha'surroun'dfifiange 6|. A cap 68 is screwed on to the outer end of member 68 until it bears against the end of abutments 56, 58,152.

these members. radially somewhat beyond the depth of vanes 5t and 58 to provide a fluid seal betweeniab-utments 62 and 64 and the wall iportion of outer member "54. ssfl flange '6! 'isiprovided in its periphery with -a ring grove.in which is a sealing ring '12. A --similarxtring M is -provided'around cap 68. The ring grooves are extended in depth, in reduced :form, beyond the inner circumference -of the rings, as indicated at 16 and 'I8-(Figs. land 2) to provide relatively thin annular fin-like flange portions of 'each member GI and 68 in contact rwith the correspon'dingends of 'member 54 and disposed'between the ends of the outermember -'54 and the corresponding sealing rings "I2 and 14. The purpose of these flexible flangerportions 'is to'maintain constant contact'with the ends of the'v'anes. 'As the sealing rings prevent-external leakage of the assembly'atthispoint, any fluid passing the shoulders into the recesses creates sufiicient pressure'for proper seating of thefinlik'e' flange' portions 'onetheiend of the vanes.

Aftertheelements 60,'65,"54 and '68 have been assembled as indicated above rand tested, themotor isinstalled asa nnit in the hollowend of the blade. Preferably .th'eoutsideidimensions ofthe motor and-the inside dimensions of rtheblade are such as to provide a push fit between the-outer Pme'mber BII and the blade to secure the-fmotor firmlyiinithe blade ends and insure its remain- Iing'in proper-alignmentwith the blades. Inth'e embodiment illustrated the outersurface of the unotor contacts the inner surface of the blade at 'two spaced locations 80 and'B2 and the blade itorquelis 'transrriittedifrom'rthe outer member-54 the motor to the blade through-a serrated or IspIined connection M :(F'ig. 2)

fIhebottom portion:of'outerz-member 3 :is' pro- ;vided"w'ith: an "outwardly {projecting wannular .flange' 86wvhichtunder1ies=the root end of blade "30 .an'd'has; on a' portion ofits circumference, .a gear sector 88 the teeth oli-ewhich meshwithnthe teeth of a'blade .sync'hronizingigear 99 rotatably mounted inra:ball bearing 9'I inrhublmember I E6. The .cooperationof the beveled gear. sector 88 of each motor and :the blade bevel gear .90 insures simultaneous.andisimilar .pitch changes of all blades.

Slight adjustmentsini pitch between the several Iblade's toobtaina condition ofaerodynamic :balance may be accomplished manuallyby utilizing the adjustablefeature, indicated at 92, of the-gear-Sfi (Fig. 1). :Gear SB-has three separate segments-eachwneof :whieh meshes With-one of .theseparate sectorsandrthe continuous hub-p01 Flange BI and cap Iiiiextend 4 tion. This adjustable featureis particularly illustrated and described in United States application Serial No. 361,565, filed October 17, 1940, by John E. Anderson, now,.Patent .No. 2,396,630 for Blade Adjusting Means; and assigned to the assignee of this application.'

The bottom of inner member 60 is provided with a pair of diametrically opposed partly cylin- "dri'cal lugs fifi and 98 (Fig. 6), and is also provided cavities formed by the assembled "position 'of' with four circular sockets, two of which are indicatedat I112 and I04 in Fig. 4, which receive the tubular flanged connectors I06, I98, III) and .112. Asis shown in Fig. 4 each of these connectors is provided intermediate its length with an outwardlyextendingflange, and has reduced diameterend ,portions received in corresponding .wellsorzrecesses in'the bottom of the inner motor member 60 and in the hub member ID. Depressionsiiflfl reduce weight of member 50.

'sides'of each pair'of blocks H8, I20. 'blocks M 8 and IZIIthere is a-wedge I22 adjust- .able by meansof a nut I24i-threaded into the hub When the blade andimotor are installed in the propeller hub :the blade and motorrcombination is broughtto aposition in which lugs 3G and .98 have their center line in a plane-perpendicular to'the axis of shaft I2. In this position the lugs will fit into cylindrical: recesses I I5 provided in hub -I0,-and the corresponding lugs of adjacent blades will be brought into'close proximity between each pair of adjacent sockets. The surface of each lug 'facing'an adjacent lug is flattened,-as indicated at H4 and l l6 (Figs. 2 and 6) and these flats bear against the-ends of slidable blocks shown at H8 and I20 in Figs. 2 and 3.

For convenience in assembly a strap H9 (Figs. 2 and 3) is placed, as shown, inrgrooves in the Between packing 132 "expanded in position between the .connector'andthewall-of' the socket. This packing is held in relation .to the connector by the compression spring I3 3. Preferably the sockets in'the hub member are of sufiicient size to just receive the flanges on the connector-members.

When the blade-motor combination is inserted in itsblade socket, wedge 122 is retracted, permitting blocks H8 and I20 to move toward each other and permitting theblade and motor combination to move inwardly beyond its normal operating position in the blade socket. When this occurs connectors I06, I08, III] and H2 will be forced into'the corresponding sockets in the hub member, the flanges of the connectors compressing springs I34. With the blade and'motor combination in this position-the bearing balls are inserted'in the corresponding race grooves, after which wedge members I22-a1'e forced in by nut I24, forcing the blade-motor combinations radially outwardly until each blade bearing is given the desired preloading .to'maintain the blade in firm association with its corresponding socket. When this occurs, springs I34 force the packings and connectors outwardly. and maintain the'fiuid seals. In addition to-servingas abutments for preloading the blade retaining bearings, lugs 96 :5 and 98 also serve to prevent rotation of the inner portion of the motor and thereby resist the torque reaction during the pitch changing movements of the motor.

Fluid may be supplied by a pump I36 as diagrammatically illustrated in Fig. 1, and the con- .nection of the pump outlet with either side of the motor and the connection of the opposite side of the motor with the sump I38 may be controlled by a speed responsive device such as a governor indicated at I40. Two fluid lines I42 and I44, which may be alternatively pressure or drain lines depending upon the direction of pitch change required, are led through a suitable transfer bearing-I46 (Fig. 1) to a pair of channels I48 and I50 connected with manifolds I52 and I54. I

While a suitable hydraulic system for supplying pressure fluid to and draining exhaust fluid from the motors has been diagrammatically illustrated, it is to be understood that the invention is in no way limited to any particular system but that various other hydraulic systems may be used such, for example, as that particularly illustrated and described in co-pending United States application Serial No. 77,644, filed February 21, 1949, by Donald W. Perin and Nelson R. Richmond, for Propeller Control Means, and assigned to the assignee of this application, which is a continuation of application Serial No. 664,640,

filed" April 24, 1946, now abandoned, which in turn is a continuation of application'serial No.

422,252 filed December 9, 1941, also abandoned, in which the source of fluid under pressure is a pump carried by and rotatable with the propeller hub and in which a fluid distribution valve is disposed in the propeller hub and hydraulically interposed between this pump and the pitch changing motors.

As explained above, and as particularly illustrated in Fig. 6, there are four connectors associated with each pitch changing motor, two being connected with one side of the motor and the other two with the opposite side of the motor. For example, connectors I08 and H0 are .con-

nected with one side of the motor through-channels I56, I58 (Figs. 1 and 6) while connectors I06 and IIZ are connected with the opposite side of the motor through the channels I64, I66, I68, I and I72. Thus for each motor there is one pair of connectors associated with one side of the motor and another pair associated with the opposite side. One of the manifolds I52 or I54 is connected with all passages in the hub member associated with one pair of connectors and the other manifold is connected with the other pairs of connectors. By referring to Figs. 4 and 6' it may be seen that the passages include channels, as indicated at I14, connecting adjacent hub member sockets in the same plane at right angles to the axis of rotation of the hub, and fluid channels in the inner motor member connecting the sockets of each pair together and with the motor chambers. It will be noticed that some fluid channels, such as I62, I12 are annular grooves cut in the outer surface of inner member 60 within sleeve 54.

In order to prevent leakage of fluid past the various motor vanes and abutments, their surfaces are covered by flexible packing formed of resilient material indicated at H6 in Fig. 5, and each packing member is held in place by a generally cup shaped washer member as indicated at I18. The washer members for abutments 62 and Marc held in place by rivets I80 while each washer member for vanes 56 and 58 is held in I86. receive a lock pin (not shown) for preventing acplace by a rivet I82 extending through member 54;

In the modified form of the device shown in Fig. '7 the wedge members particularly indicated at H8, I20 and I22 in Figs. 2 and 3 are omitted and the hub member I0 within each blade socket 24 is provided with an internally screw threaded boss I86 coaxial with the blade socket. The inner member 60' of the vane'motor is internally threaded to receive a hollow plug I68 having a lower end surface adapted to contact the outer surface of the boss I86, and provided in its lower end with a wrench socket I90.

The blade retention bearings may be preloaded by manipulation of the plug I88 in the following manner.

. Before a blade is inserted in a blade socket the plug member I88 is inserted in the end of the center post 60' and screwed upwardly, as viewed in Figure '7, to a position which will permit the base end of the blade to move into the socket to the maximum extent, at which position of the blade the balls may be inserted as previously described. After the balls have all been inserted, a wrench is inserted through boss I86 into socket I90 in plug I88 and this plug is screwed down, as viewed in Figure 7, to force the blade upwardly in the blade socket, the incidental reaction being taken by pressure of the end of plug I88 on boss Holes I89 arev provided in the plug I88 to cidental movement of the plug after it has once been adjusted. After plug member I88 has been moved a suflicient distance to apply the proper preloading to the blade bearings a plug I92 is screwed into the hole in boss I86 to prevent passage of lubricating fluid to the interior of the shaft-surrounding portion of hub member I0.

In this modified form of the invention it is to be noted that instead of the integral fin-like flange portions particularly illustrated in Figs. 1 and 4, separate washers, one of which is indicated at I94, are used to seal the ends of the vane motor. Any fluid passing the shoulders into the recess I95 creates sufficient pressure for proper seating of the separate ring on the end of the vanes. The seal ring 12 isretained in this modification'and an additional endless thrust ring I96 is added providing a centering action for the internal parts and also having the function of retaining the seal ring I2 in position for assembly. After rings I94 and I2 are assembled in position ring I96 is slipped over ring I2 and left in position to compress this ring into the annular groove provided for it in the periphery of washer I94. Then as'the outer member 54 of the motor is brought to assembled position ring I96 is moved down to the position illustrated in Fig. 7 and ring I2 is held in operative position by the circumferential lower end of member 54, ring I96 being forced down into a peripheral recess provided for it in the lower flange portion of the inner member 60' and resting against an annular shoulder at the bottom of this recess.

The above sealing construction including sealing washer or plate I94 disclosed in this application is claimed in a continuation application, Patent No. 2,550,180, issued April 24, 1951, of Arthur N. Allen, Jr.

It will be appreciated from the above that the fluid motor is complete in itself and may be assembled and tested as a unit entirely independently of the hub-blade assembly.

While a suitable mechanical embodiment has been hereinabove described and illustrated in the zaccompanyingidrawings :for -the purpose :of-1dis closing the invention, it is to be understood that .ithe 'invention is. not limited-toithe particularrembodiment so .illustrated 1 and :described, :but that -;such changes inthe size, shape: andzarrangement of the various parts :may besresorted :to as come within the scope of the subjoinedclaims.

fi-Iaving now described the invention so :that {others skilled in the'art may:clearlypunderstand :the same, whatit is desired to secure by Letters :Patent is as :follows:

.L. In combination 'with aaicontrollablepitc'h propeller having aplur'alitypf blades andcat-blade 'retaining hub, .individual motors'for rotating said z-blades in pitch changing directions each comprising a hollow outer portion fixed in the-hollow root end of ablade,:andan inner portion separate i from said hub within said outer portion, said *inner and outer portions being rotatable relatively toeach other,recesses in saidpropeller hub, and a pair of lugs on each inner portion'seated 'in said recesses in said propeller hub 'to restrain 'said inner portion against rotation relative to said hub, corresponding recesses in said inner motor portion and saidhub memberconstituting "a pair of recesses, and a tubular connector-slidably received ineach pair to provide'flexible fluid -connections between said hub-member :and said motor.

2. The arrangement as set forth in claim 1 in which each of said-connectors is'provided intermediate its length-with an external flange, one of each pair of corresponding recesses being of proper size to slidably receive said flange, and a packing member surrounding each connector within the flange-receiving recess.

3. The arrangement as set forthinclaim "1 in which each of said connectors is providedintermediate its length with an external flange and in which the connector'receiving recesses in said hub member are suflicient'in size to receive said flanges, a packing member surrounding-each connector within its'recess, and a'compression spring holding each packing member in position against its corresponding flange and urging the corresponding plug out of the recess.

4. In combination with a controllable-pitch propeller having a plurality of blades and a blade "retaining hub, individual motors for rotating said blades in pitch changing directions, each motor comprising a hollow outer portion fixed in the hollow root end of a blade, and an inner portion separate'from said hub within said outer portion, said inner and outer portions being rotatable relatively to each-other, recesses in said propeller hub, a pair of lugs on each inner portion seated in said recessesin said propeller hub to restrain said inner portion against rotation relative to said hub, corresponding recesses in said inner motor portion and said hub member constituting a pair of recesses, a tubular connector slidably received in each pair to provide 'fluid connections between said'hub 'andsaid motor, and continuous-fluidpassages connecting all of'said motors and constituted in part'bysaid connectors.

5. A'fluidmotorcomprising an innerlmember provided with radially extending abutments, an outer member surrounding said inner -member 'and' providediinternally .with radially extending vanes disposed between the abutments onsaid inner member, flanges on said. inner :member: at the ends of said tabutmentsuandextending beyond said vanes,:said:flangesbeingreceived in -.8 'iber, one :of "said 'flangeswbeing :detachable' from :saidrinner member.

6. 'A'fluid motorcomprising an-innermember provided with radially extending abutments, an outer member surrounding said inner member and :provided internally with radially extending vanes disposed between the abutments :on said inner member, flanges on said inner member at the ends of said vanes extending beyond said =vanes and received in circular recesses in the ends of said outer member, one of said flanges 'being detachable 'from said inner 'member, ring grooves in said flang es and sealing rings in said grooves, said -grooves being extended. inwardly in reducedsection .to'provide flexible, fins integral with said flanges and .in. contact with .the bottoms of the recesses in said outer .member. '7. Afluid motor comprising an inner member provided with radially extending abutmentsh an .outer member surrounding .said inner member and provided internally with radially ,extending vanes disposed between the abutmentson said inner member, .flanges ,on saidinner membenat the ends of said vanes, said flanges extending beyond said :vanes and being received in circular recesses in the ends of said outer member, said inner member comprising a core member provided with grooves in the surface thereof constituting fluid channels, and a tubular abutment .carrying member fitted over said core member :andcovering said grooves.

'8. In a controllable .pitch propeller having a plurality-of blades retained in'blade receiving sockets in a propeller hub, individual motors for rotating said blades in pitch changing directions each comprising a hollow outer portion fixed in the hollow root end of a blade and an inner portion separate from said hub within said outer portion, said inner and outerportions beinggrelatively rotatable, recesses in said propeller hub, and a pair of lugs on each inner portion extending longitudinally of said blade and seated in said recesses in saidpropeller hub to restrain ,said inner portion against rotation relative to said hub, corresponding .recesses in said.inner motor portion and said hub member, and a plurality of tubular connectors slidably receivedin said corresponding recesses extending longitudinally-of saidblade to provide .fiuid connections between saidhub-member andsaid motor, :said .lugs, said .recesses and said corresponding re- .cesses all-extending"substantially-parallel to the ;axis of the blade receiving socket so that the -lugs'may beainscrted into their recesses and the tubular connectorsmay'beinserted in their corresponding recesses'by insertion of the blade in itssocket.

'9. A pitch changing fluid motor for rotating the blades of a controllable pitch propeller in pitch changing directions, comprising a hollow outerportion adapted to be attached to the hollow-root end of a propeller blade, an inner portion within said outer portion, said inner and outer portions being rotatable relative 'to each otherby fluid under pressure, a socket for re- .ceiving said motor, recesses in said socket,,and apair of lugs oneach inner portion seated in said recesses to restrain said ,inner ,portion against rotation, corresponding recesses in said innerzmotor portion and said socket, .and-a pluralityeof'tubular connectors slidably received :in

.circular;r.ecesses in the-ends=.of.;said@outermiem- Inc said corresponding trecesses .to provide flexible 9 fluid connections between said hub member and Number said motor. 2,013,647 JOHN E. ANDERSON. 2,307,101

ARTHUR N. ALLEN, JR.

REFERENCES CITED Number The following-references are of record in the file of this patent: 857,521 UNITED STATES PATENTS 10 346563 Number Name Date 147,228

853,999 Schmid May 21, 1907 Name Date Bace Sept. 10, 1935 Blanchard et a1. Jan. 5, 1943 FOREIGN PATENTS Country Date Great Britain Dec. 20, 1937 Great Britain Sept. 4, 1941 France Apr. 22, 1940 Germany Jan. 4, 1922 Switzerland Aug. 17, 1931 

